Combined steam electric drive for generator sets



? May 21, 1929. R. E ROYsE 1,714,449

COMBINED STEAM ELECTRIC DRIVE FOR GENERATOR SETS Filed July 5, 1928 ATTORNEY' Patented May 21, 1929.

UNITED STATES PATENT OFFICE.

RALPH E. ROYSE, OF TACOMA, WASHINGTON.

COMBINED STEAM ELECTRIC DRIVE FOR GENERATOR SETS.

Application filed July 5, 1928. Serial No. 290,561.

for normal generatc-r'load with dual gen-' erators uniformly spaced therefrom on the shaft and steam turbines beyond the generators having a joint capacity under full head to impart initially full driving torque to the shaft without generator load, there'- after for normal operation, functioning under reduced head, with the added power of the central driving motor maintaining the full torque of the shaft and automatically varying and accommodating its power input to variations in generator load. In order to apply and economically to usethe power of the central drive motor, the central section of the shaft mounting the'motor, which motor is necessarily larger than gener'ators and turbines, is of enlarged diameter with the adjoining shaft portions mounting the generators and turbines having a relatively smaller diameter proportioned to their size and power torques.

' In three unit sets comprising an elastic fluid turbine, electric driving motor, and electric current generator or other driven machine on a common shaft, it has been the practice to use the motor for normal drive of the shaft, an automatic governor or throttling mechanism being used to cut in the supply of elastic fluid to the turbine when through the load of the generator or other machine, or failure in the current supply to-the motor, the R. P. M. speed falls below that set by the governor; In such installations as ordinarily operated, the motor, usually, an alternating current motor, is connected to the main bus bars of a current supply line so that its speed is set by that of the main generator supplying, current to the line, the governor of the turbine being set for a speed lower than the normal motor speed. These sets are ordinarily used as auxiliaries to the main power plant. The arrangement of steam-electric drive involved in the present invention, while suitable foruse in its. smaller sizes of units as an auxiliary "to large main set installations is more economically adapted for the main power set itself, and will be described and illustrated as used in this connection.

Current to the main driving motor is supplied, for example, from one or more motor driven generators which nay economically be of the Diesel engine type. By preference, a single Diesel motored generator is employed having adequate capacity for normal full generator loads.

The described arrangement of motor, generators and turbines not only provides a balanced load on the shaft of the set and permits the use of a shaft giving maximum motor torque and minimum shaft load, but provides a normal motor drive automatically adapting its current input to variations inshaft and generator load with the turb1nes functioning under reduced pressure head during normal operation to reduce the load of turbine and generator rotors on the shaft and effective. to initially bring the shaft up to speed. Additionally, for ship installation, the turbines may be operated under full head to turn over the shaft to furnish current for the lighting plant with the ship at anchor or docked, the central motor drive being used when the generator load increases, as when the ship is under Way'and generator current is used for propulsion, or when electric hoists are being operated. The full pressure head operation of the turbines may also be utilized in emergenome to supplement the main central motor drive as when generator output is used for ship propulsion at maximum emergency speed, or the maximum output of the generator set is required in an emergency in a land power plant installation.

The combination of steam and electric drive for the generator set therefore makes it flexible to all conditions of power requirement. The central driving motor will act as a compensator, varying its input of current responsively to generator load, the current requirements of the central drive motor being met by the generator 13 through the usual governor used with engines driving generators, the'type of governor varying with the speed type of motor andthe nature of the current generated, its effect being to vary'the speed of the generator driving motor responsively to the current load placedon its generator,

The ifr'ivention in its details will be more clearly apparent by reference to the follow r the shaft and thefbearings 4 adjacent to the shaft mounting said elements.

yond the generators. ported'in suitable centralbearings 3 3 and ing specification and to the accompanying drawings forming part thereof and in Which: i

Figure 1 is a plan view of'a 'lineshaft mounting steam-electric driving and current generating elements in accordance with the present invention, the circuit for the'central motor drive and the leads from the generatorsto adistributing board being indicated diagrammatically. v

Figure 2 1s a plan view ofthe-s1ngle drive The steain electric drive of thepresent inventionls, as before statechinounted upon a single line o'rlength of-shafting which, as 7 shown in Figure 2, comprises a centralportion 1 -o'fmaXimum diameterand' relatively short length carryingthe rotorofa direct current motor of suitable power, and, ad jacentfportions 26f a reduced diamete-r'upon which are mounted at'eac'h side of the rotor section, dual alternating current. generators,

with steam turbines :coupled to the shaft be- This shaft isjsup end be'ari'ngs i4t t carried 'in standards 5 bolted to and uprising from a suitable base '5fwhich'm'ayibe the deck or flooring-of the "engine 'room' of 'avessel, or the floor of a shore power plant, for example.

Theframe T of he central electric driving'moto'r'8 is bolted, to the base support 6 and' is preferably a direct current motor of standard type' and suitable power to '-the terminals 9 and r'10of which current may be supplied throughleads 11 and12 fromcrnotor driven'generator 13 ofrs ize and power output capable of ansvveringthe full powerirequiremeiitsof the motor v8 Advantageously the generator ,13 may be provided of the 'Diesel motor-driven typetoprovide loWifuel and operating costs, and relatively small fuel ,storage space, a suitable irheostat 15 being interposed, to :provide for the cutting in and out ofthe current from the "generator 13 to the motor 8. At the opposite'ends of the motor 8, the dual alternating current generators 16, are mounted uponthe 'reduced :portionsl2 of the drive shaft between the board to -be'*used for any .-purpose, forexcentral bearings3 for the driving'section of enjds'of the shaft. The casings of thesegen- "erators-are, as shovvmbolted to the basefi similarlyto the motor casing 7. ,The alter-v nating current generated through operation ofthe generators is carried by theleads 17 and 18 to bus'bars on a maindistributingample, such as furnishing the power for the lighting; plant of a ship, for auxiliary "motors to;be used for hoists, etc.,-or for 'apropeller shaft vor shafts as diagrammatically illus- 'E-ThedualEturbines in-additionto their function as starting motors have, the advan- 'tage when operating under a reduced head of steam during shaft drive through the cen- "an motor 8, of providing means for relievingthe load of Zth'e turbine and generator rotors on thedrive shaft, and as previously state'cl,-may be used m -emergencies to supplement themotor drive of the shaft, and in- I de 'endentl of the motor drive for minimum generator load, as when a set of this character 18 installed as tnema npower plane of a vessel as previously recited,"and with f the vessel anchored, n'ioored'ordocked, the

current output of the generators is'to be used only "forthelighting plant. f

Onthefends of the reduced sections '2 of the drive shaft are "mounted the rotors'of steani turbi'nes '19, the casing 20 of which are bolted'to the baSe'G. Steam is fed'to these turbines,'wliich may be of any standard construction, through feed pipes 21 extending from a suitablesteamboilen 7 V These turbines, as previously explained,

are used to start'the revolution of the drive sired RP. ll LspeedQ V p i I flVhat I 'c'laim,there'fore, and desir'eto secureby Letters Patent is: v

7 .1. A generator set comprising, in combination, a shaft mOu'nted 'for rotation, an electric driving motor having its rotor mounted *thereon, a source of electric ouro .main'tain'the shaft in'rotation at the demrent'for said-motor flexible"to th'efload de- 7 mands of the shaft thereon, dual electric generators having their "rotors mounted on said shaft adjacent to andat each side of said "driving'motor' and a pair of steam turbines having their rotors mounted on the shaft beyond and adjacent to eachojf said generators and having' a. maximum joint ,power output capable of imparting 'full speed of revolution to said shaft Without 1 generator load thereon, said driving motor hav ng a maximum power, output 7 cap able of jmaintaining full speed of shaft revolution .:under full generatorlload, a

s 2. generator set comprising, in com bination, a shaft mounted for-rotation, an "electric; driving motor having its rotor mounted thereon, a motor-driven generator supplying current to said driving motor responsive to the demands of the shaft load thereon, dual electri c," generators" having their rotors mounted on saidishaft adjacent to each side of said motor, and a pair of steam turbines'having their rotors mounted .on the shaft beyond and adjacent to each of said generators and having a maximum joint power output capable of imparting full speed of revolution to said shaft without generator load thereon, said driving motor having a maximum power output capable of maintaining full speed of shaftrevolution under full generator load.

3. A generator set comprising in combination a shaft mounted for rotation and having a driving motor section of increased diameter formed thereon, an electric driving motor therefor having its rotor mounted on said section, a generator for supplying current to said driving motor, a coupled explosive motor for driving said generator governor-controlled to vary the speed of the explosive motor and output of its generator responsively to variation in shaft load on the electric driving motor, dual electric generators having their rotors mounted on said shaft adjacent to said section of increased diameter and at each side of the driving motor, and a pair of elastic fluid turbines having their rotors mounted on said shaft adjacent to and beyond each of said generators and having a maximum joint power output capable of initially imparting full speed of revolution to the shaft without generator load thereon and with the driving motor inoperative, the latter having a maximum power output capable of maintaining the full attained R. P. M. speed of the shaft with full generator load thereon and, with the turbines operating under reduced pressure head to relieve the load of turbine and generator rotors, functioning automatically to compensate for and vary' its power input with variations in generator load. on the shaft.

RALPH E. ROYSE. 

